The field of this invention relates generally to systems for applying an elastic band around a product, and more particularly to systems for expanding and placing at least two elastic bands around a stack or bundle of individual items.
Schemes have been devised in the past for applying elastic bands as in the form of rubber bands around products, notably in the field of irregularly shaped foodstuffs such broccoli. U.S. Pat. No. 4,401,020 to Brux discloses a complex conveyor belt system for routing the broccoli or other product being prepared for banding. The product is finally routed to a banding station, where the product is dropped vertically into the center of a band stretching assembly which has already expanded the elastic band. Upon landing in the orafice provided by the stretching fingers and elastic band, the fingers collapse until the band is supported by the product and then the fingers are withdrawn to release the band. After banding, product drops free and is carried away. This system depends upon the irregular shape of the broccoli to release the band from the fingers.
U.S. Pat. No. 2,601,547 to Minock discloses an expander tool for elastic bands. The bands are manually placed on a circular array of moveable fingers. Handles are then squeezed for radially moving the fingers to thereby expand the elastic band. The product to be banded is manually inserted into the open center of the expanded band, the expanded band is released, and the band snaps onto the product. Even though this construction is simple and inexpensive, it does not lend itself to high production volume. Additionally, it is labor intensive because it must be operated by a human user, and is therefore costly.
U.S. Pat. No. 4,442,765 to Limehouse et al. discloses a device for preparing produce or other products for shipment. After being manually sized at a cutting station, the product is manually moved to and inserted in a banding station. Before moving the product to the banding station, the human user must manually expand an elastic band and place it over a plurality of upwardly extending spring loaded fingers. After placing the produce through the now expanded elastic band, the user depresses a foot pedal which is connected to pull the fingers downward to release the elastic band. The band snaps onto the product, and the product is manually moved to another station.
The Limehouse approach has several disadvantages. It is labor intensive; the product and the elastic band must be manually handled by a human operator. This is expensive and relatively slow. The approach is not suitable if there are a plurality of products to be banded, as for example if the product were asparagus or a stack of individual items such as individual sheets of paper. The device does not lend itself to retrofitting into an existing assembly line; individual items of product can fall through the central opening of the expanded band, and the banding device itself must be centered around the product to enclose it so the banding apparatus structure would impede movement of other cooperating structures. Elastic bands can only be applied with the product in one orientation; it is not possible. for example, to tilt the product for installing an elastic band at a second and differing orientation.